JP4340572B2 - Planographic printing plate precursor - Google Patents

Description

  The present invention relates to a lithographic printing plate precursor, and more specifically, a positive type lithographic plate capable of direct plate making by scanning exposure based on a digital signal, excellent in printing durability, and free from stains on non-image areas. It relates to the printing plate precursor.

In recent years, with the development of solid-state lasers and semiconductor lasers having a light emitting region from the near infrared to the infrared, systems using these infrared lasers are attracting attention as a system for making a plate directly from digital data of a computer.
Among them, as a positive lithographic printing plate material for infrared laser for direct plate making, for example, a substance that absorbs light and generates heat in an aqueous alkali-soluble resin, and a positive photosensitive compound such as quinonediazide compounds (For example, refer to Patent Document 1). In the image portion of such a positive lithographic printing plate precursor, the positive photosensitive compound acts as a dissolution inhibitor that substantially reduces the solubility of the aqueous alkali-soluble resin, and in the non-image portion, it is decomposed by heat. The dissolution inhibiting ability is not developed, and it can be removed by development to form an image.

  On the other hand, it is known that onium salts and compounds capable of forming a hydrogen-bonding network with low alkali solubility have an alkali dissolution inhibiting action of alkali-soluble polymers. As an image recording material compatible with an infrared laser, it is known that a composition using a cationic infrared absorbing dye as a dissolution inhibitor of an alkaline water-soluble polymer exhibits a positive action (for example, see Patent Document 2). . This positive action is an action in which the infrared absorbing dye absorbs the laser light and the generated heat disappears the effect of suppressing the dissolution of the polymer film at the irradiated portion to form an image.

  With respect to the support used for such a lithographic printing plate precursor, there has been extensive research on hydrophilicizing the surface of the support in order to prevent contamination of non-image areas. For example, when a metal support such as an aluminum plate is used as the support, an anodized aluminum substrate (support), or silicate treatment of the anodized aluminum substrate to further increase the hydrophilicity, etc. Various techniques have been proposed. However, various treatments for improving hydrophilicity are not necessarily excellent in affinity with the recording layer, and in some cases, the adhesion between the support and the recording layer formed thereon is lowered. Therefore, the recording layer peels off under severe printing conditions, and there is a problem that sufficient printing durability cannot be obtained.

  Thus, in order to improve the adhesion between the hydrophilic support surface and the recording layer, a method of providing various intermediate layers between the support and the recording layer has been proposed. In such a method, a resin material constituting the recording layer or a material having a functional group excellent in affinity with the support surface is used as an intermediate layer. Adhesion is improved and sufficient printing durability is obtained. However, in the non-image area, the recording layer is not quickly removed at the time of development, and remains as a remaining film on the surface of the support, causing ink to adhere to the non-image area and causing stains. was there. For this reason, a support having excellent surface hydrophilicity and satisfying both the adhesion to the recording layer in the image area and the recording layer removability in the non-image area has been desired.

In order to solve the above problems, a lithographic printing plate provided with an intermediate layer containing a polymer compound containing a specific structural unit such as p-vinylbenzoic acid has been proposed (see Patent Document 3). A lithographic printing plate precursor provided with an intermediate layer containing a polymer (random polymer) having a monomer having an acid group and a monomer having an onium group has also been proposed (see Patent Document 4). Although these have a certain improvement effect, the adhesion between the support and the intermediate layer, the intermediate layer and the recording layer is improved, and the printing durability is further improved. However, the present situation is that further improvement that effectively suppresses the generation of dirt is desired.
JP-A-7-285275 International Publication No. 97/39894 Pamphlet JP-A-10-69092 JP 2000-108538 A

An object of the present invention is to solve the conventional technical problems and achieve the following objects.
That is, an object of the present invention is to provide a lithographic printing plate precursor that can be directly made by scanning exposure based on a digital signal, has excellent printing durability, and does not cause stains in non-image areas. .

As a result of extensive research, the present inventors have found that the above problem can be solved by providing an intermediate layer containing a polymer having a specific ionic structure between the support and the recording layer. The present invention has been completed.
That is, the lithographic printing plate precursor according to the invention has, on the support, a cation structure, a counter anion containing an alkali dissociable proton-containing group and a sulfonate ion (—SO ₃ ⁻ ) in the side chain. An intermediate layer containing a polymer having a repeating unit as a constituent component (hereinafter referred to as “specific polymer” as appropriate), and a photosensitive positive recording layer whose solubility in an aqueous alkali solution is improved by exposure are provided in this order. It is characterized by.

Here, “provided in this order” means that an intermediate layer and a recording layer are provided in this order on a support, and other layers (for example, a protective layer, a backcoat layer, etc.) provided according to the purpose. ) Is not denied.
In addition, the photosensitive positive recording layer used in the present invention may be any one as long as the solubility in an alkaline aqueous solution is improved by exposure, for example, a conventional positive type recording layer or a thermal positive type recording layer. A recording layer can be used.

Although the operation of the present invention is not clear, it is considered as follows.
That is, the specific polymer contained in the intermediate layer according to the present invention has a ionic structure consisting of a cation structure and a counter anion in the side chain, thereby forming a strong interaction with the surface of the support that has been hydrophilized. Therefore, it is considered that the adhesion between the support and the recording layer is improved, and as a result, the printing durability can be improved. Further, since the counter anion in the specific polymer contains a group having an alkali-dissociable proton, the dissociation property with respect to the alkali developer is improved by the presence of this group. Therefore, the intermediate layer containing the specific polymer is developed. Sometimes dissolved and dispersed easily by contact with an alkaline developer. Therefore, in the non-image portion of the lithographic printing plate precursor having such an intermediate layer, the recording layer and the intermediate layer are removed together to expose the hydrophilic surface of the support without generating a residual film. It is considered that the occurrence of contamination in the non-image area can be effectively suppressed.

  According to the present invention, it is possible to provide a lithographic printing plate precursor which is capable of direct plate making by scanning exposure based on a digital signal, has excellent printing durability, and does not cause stains in non-image areas.

Hereinafter, the present invention will be described in detail.
The lithographic printing plate precursor according to the invention has a repeating unit having a cation structure, a group having an alkali dissociable proton and a counter anion containing a sulfonate ion (—SO ₃ ⁻ ) in a side chain on a support. An intermediate layer containing a polymer-specific polymer having the above-mentioned constituents, and a photosensitive positive recording layer whose solubility in an aqueous alkali solution is improved by exposure.

[Middle layer]
The intermediate layer containing the specific polymer in the present invention will be described. First, the details of the specific polymer will be described.

[Specific polymer]
As described above, the specific polymer in the present invention constitutes a repeating unit having a cation structure, a group having an alkali dissociable proton and a counter anion containing a sulfonate ion (—SO ₃ ⁻ ) in the side chain. Ingredients.
The specific polymer in the present invention preferably has a partial structure represented by the following general formula (I).

In the general formula (I), P represents a polymer main chain, A represents a q + 1 valent linking group, and Y represents a cation structure. Z represents an anion moiety containing a sulfonate ion in the counter anion, and X represents a group having an alkali dissociable proton covalently bonded to Z. n represents an integer of 1 to 3, and q represents an integer of 1 to 3.

  P in the general formula (I) is a polymer obtained from a repeating unit such as an acrylic unit, a methacrylic unit, an acrylamide unit, a methacrylamide unit, a styrene unit, a vinyl unit, an ester unit, an amide unit, a urethane unit, or an ether unit. The main chain is mentioned. Among them, a polymer main chain obtained from an acryl unit, a methacryl unit, an acrylamide unit, a methacrylamide unit, and a styrene unit is preferable.

In the general formula (I), the cation structure represented by Y is obtained by adding a proton to a neutral atom or atomic group or emitting electrons, and functions as an electron pair acceptor. If it is the structure to do, there will be no restriction | limiting in particular.
Specifically, it may be a cation structure in which protons are added to the atomic groups constituting the side chain of the polymer chain represented by P or electrons are emitted, or represented by P. When the side chain of the polymer chain contains an element having a lone pair, it is a cation structure formed by coordination of a proton or cation type atomic group to the lone pair, so-called onium ion. May be. Among them, the cation structure represented by Y is preferably the latter onium ion, and the element having the lone electron pair is more preferably an onium ion that is a group V or group VI atom in the periodic table. preferable.

In the above general formula (I), the q + 1-valent linking group represented by A links the polymer main chain represented by P and the ionized atom (element) in the cation structure represented by Y. Specifically, the q + 1 valent linking group includes -COO-, -CONH-, a phenylene group which may have a substituent, and the like resulting from the repeating unit constituting the polymer main chain represented by P. In addition, an alkylene group, an aromatic group, a substituted aromatic group, —S—, —SO ₂ —, —SO—, —CO—, —O— and combinations thereof are mentioned, among others, COO—, —CONH—, an optionally substituted phenylene group, alkylene group, aromatic group, and substituted aromatic group are preferred.
In addition, these groups may further have a substituent, and examples of the substituent include an alkyl group, an alkoxy group, a hydroxyl group, a halogen atom, a cyano group, and a nitro group.

In the general formula (I), the anion portion position comprising sulfonic acid ion represented by Z includes a sulfonate ion is luer anion structure to correspond to the conjugate base of a Bronsted acid, and, later, X There is no particular limitation as long as it is a group that can be covalently bonded to.
Specifically, the anion portion position is, R -SO ₃ ^- is a group represented by. In here, R may be an optionally substituted hydrocarbon group, or represents a phenylene group having a substituent, Ar represents an aryl group which may have a substituent. Here, examples of the substituent that can be introduced include a halogen atom, a nitro group, an alkoxy group, an alkyl group, an amino group, a cyano group, an amide group, an ester group, and a carbonyl group.

Examples of the group having an alkali dissociable proton represented by X in the general formula (I) include a phenolic hydroxyl group (Ar—OH), a carboxyl group (—COOH), a mercapto group (—SH), a phosphonic acid group ( —PO ₃ H ₂ ), phosphoric acid group (—OPO ₃ H ₂ ), sulfonamide group (—SO ₂ NH ₂ , —SO ₂ NHR), substituted sulfonamide acid group (hereinafter referred to as “active imide group”). _{-SO 2 NHCOR, -SO 2 NHSO 2} R, -CONHSO 2 R), sulfonic acid (-SO ₃ H), sulfinic acid group _{(-SO 2 H), - C} (CF 3) 2 OH, -COCH 2 COCF ₃ is preferably used. Here, Ar represents an aryl group which may have a substituent, and R represents a hydrocarbon group which may have a substituent.

  The specific polymer in the present invention is preferably synthesized from a monomer having an onium salt structure represented by the following general formula (A) to general formula (C).

In general formulas (A) to (C), J represents a divalent linking group. K represents an aromatic group or a substituted aromatic group. M represents a divalent linking group. Y ¹ represents a group V atom in the periodic table. Y ² represents an atom of Group VI of the periodic table. Z ¹⁻ represents a counter anion composed of a group having an alkali-dissociable proton and an anion site containing a sulfonate ion that can be covalently bonded to the group. R ² represents a hydrogen atom, an alkyl group, or a halogen atom. R ³ , R ⁴ , R ⁵ , and R ⁷ each independently represent a hydrogen atom, an alkyl group, an aromatic group, or an aralkyl group, and these may further have a substituent. R ⁶ represents an alkylidine group or a substituted alkylidine group. R ³ and R ⁴ , R ⁶ and R ⁷ may be bonded to each other to form a ring. j, k, and m each independently represent 0 or 1. u represents an integer of 1 to 3.

Among the monomers having an onium salt structure represented by the general formulas (A) to (C), more preferable are the following cases.
J represents -COO- or -CONH-, and K represents a phenylene group or a substituted phenylene group. The substituent introduced when K is a substituted phenylene group is preferably a hydroxyl group, a halogen atom, or an alkyl group.
M is an alkylene group and a divalent linking group having a molecular formula of C _n H _2n O, C _n H _2n S, or C _n H _{2n + 1} N. However, n represents the integer of 1-12 here.
Y ¹ represents a nitrogen atom or a phosphorus atom, and Y ² represents a sulfur atom.
Z ^- anion position in the, R -SO ₃ ^- is. In here, R represents a phenylene group which may have a may have a substituent hydrocarbon group, or a substituent.
Furthermore, Z ^- Examples of the group having an alkaline-labile proton in the phenolic hydroxyl group (Ar-OH), carboxyl group (-COOH), a mercapto group (-SH), a phosphonic acid group _{(-PO 3 H} 2), A phosphoric acid group (—OPO ₃ H ₂ ), a sulfonamide group (—SO ₂ NH ₂ , —SO ₂ NHR), —C (CF ₃ ) ₂ OH, and —COCH ₂ COCF ₃ are represented. Here, Ar represents an aryl group which may have a substituent, and R represents a hydrocarbon group which may have a substituent.

R ² represents a hydrogen atom or an alkyl group.
R ³ , R ⁴ , R ⁵ , and R ⁷ are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms or an aromatic group having 6 to 10 carbon atoms to which a substituent may be bonded. Represents a group or a C7-10 aralkyl group.
R ⁶ is preferably an alkylidine group having 1 to 10 carbon atoms or a substituted alkylidine. R ³ and R ⁴ , R ⁶ and R ⁷ may be bonded to each other to form a ring.
j, k, and m each independently represent 0 or 1, but j and k are preferably not 0 at the same time.
R ⁸ represents an alkyl group having 1 to 10 carbon atoms, an aromatic group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 10 carbon atoms to which a substituent may be bonded.

Among the monomers having an onium group represented by the general formulas (A) to (C), particularly preferred are the following cases.
K represents a phenylene group or a substituted phenylene group, and when it is a substituted phenylene group, the substituent represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.
M represents an alkylene group having 1 to 2 carbon atoms or an alkylene group having 1 to 2 carbon atoms linked by an oxygen atom.
Z ^- definitive anion position is, R -SO ₃ ^- is. In here, R represents a phenylene group which may have a may have a substituent hydrocarbon group, or a substituent.
Furthermore, Z ^- Examples of the group having a definitive alkali dissociable proton, the phenolic hydroxyl group (Ar-OH), carboxyl group (-COOH), a mercapto group (-SH), a sulfonamido group _(-SO 2 _NH 2, - SO ₂ NHR). Here, R represents a hydrocarbon group which may have a substituent.
j is 0 and k is 1. R ⁸ is an alkyl group having 1 to 3 carbon atoms.

The specific polymer in the present invention can be obtained by polymerizing or copolymerizing a monomer having an ionic structure comprising a cation structure and a counter anion containing a group having an alkali dissociable proton by a known method. Examples of the polymerization method include condensation polymerization and addition polymerization, and a preferable method is addition polymerization.
In addition, when a specific polymer is a copolymer, any of a random copolymer, a block copolymer, or a graft copolymer may be sufficient.

  As a method for synthesizing a specific polymer, for example, polymerization initiation of peroxides such as di-t-butyl peroxide and benzoyl peroxide, persulfates such as ammonium persulfate, and azo compounds such as azobisisobutyronitrile is preferable. It can be carried out by radical polymerization using an agent. The polymerization initiator is appropriately selected depending on the polymerization method to be applied. As the polymerization method, solution polymerization, emulsion polymerization, suspension polymerization or the like is applied.

  The polymerization solvent used in the synthesis includes acetone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol dimethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1 -Methoxy-2-propyl acetate, dimethoxyethane, methyl lactate, ethyl lactate, ethyl acetate, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, toluene, water and the like. It is not limited to.

Hereinafter, although the specific example of the monomer used suitably when synthesize | combining the specific polymer of this invention is given, this invention is not limited to these.
In the specific examples shown below, monomers whose counter anion is represented by (Z ²⁻ ) are listed, but (Z ²⁻ ) described here includes specific examples of counter anions listed later. Examples can be combined arbitrarily.

Specific examples of the counter anion represented by (Z ²⁻ ) in the specific examples of the monomer shown above are shown below. As described above, (Z ²⁻ ) in the specific examples of the above monomers and the specific examples of the following counter anions can be arbitrarily combined.

  Among these specific examples of monomers suitably used for synthesizing the specific polymer of the present invention, examples of more preferable monomers are listed below.

  In the specific polymer, as described above, the content of the ionic structure composed of the cation structure and the counter anion is sufficient to improve the adhesion to the hydrophilized support and the developer solubility. From the viewpoint, 5 mol% or more is preferable, and 10 mol% or more is more preferable.

  Moreover, as a weight average molecular weight of the specific polymer in this invention, 500-1,000,000 are preferable and 2,000-200,000 are more preferable.

(Other monomer components)
The specific polymer according to the present invention may be a copolymer obtained by copolymerizing other monomer components for the purpose of further enhancing the interaction with the support or the interaction with the recording layer. Examples of the other monomer component include, for example, “monomer having an acid group” from the viewpoint of improving adhesion with a hydrophilized substrate and improving developer solubility, and “recording from the viewpoint of improving adhesion with a recording layer”. Monomers having a functional group capable of interacting with the layer ”and the like.

<Monomer having an acid group>
The monomer having an acid group that is suitably used for the specific polymer will be described.
The acid group contained in the monomer having an acid group is particularly preferably a carboxylic acid group, a sulfonic acid group, or a phosphonic acid group, but is not limited thereto.

-Monomer having a carboxylic acid group-
The monomer having a carboxylic acid group is not particularly limited as long as it is a polymerizable compound having a carboxylic acid group and a polymerizable double bond in its structure.
Preferable examples of the monomer having a carboxylic acid group include compounds represented by the following general formula (1).

In General Formula (1), R ^{1 to} R ⁴ each independently represent a hydrogen atom, an alkyl group, or an organic group represented by the following General Formula (2), and at least one of R ^{1 to} R ⁴ is: It is an organic group represented by the general formula (2).
Here, from the viewpoint of copolymerizability and raw material availability when producing the specific polymer, R ^{1 to} R ⁴ may have 1 to 2 organic groups represented by the following general formula (2). It is particularly preferable to have one. From the viewpoint of the flexibility of the specific polymer obtained as a result of the polymerization, among R ^{1 to} R ⁴ , in addition to the organic group represented by the following general formula (2), an alkyl group or a hydrogen atom is preferable. Particularly preferred is a hydrogen atom.
For the same reason, when R ^{1 to} R ⁴ are alkyl groups, they are preferably alkyl groups having 1 to 4 carbon atoms, and particularly preferably methyl groups.

  In general formula (2), X represents a single bond, an alkylene group, an arylene group which may have a substituent, or any one of the following structural formulas (i) to (iii). From the viewpoints of polymerizability, availability, etc., a single bond, an arylene group represented by a phenylene group, or one represented by the following structural formula (i) is preferred, and an arylene group or the following structural formula (i) is preferred. Those represented by the following structural formula (i) are particularly preferred.

In structural formulas (i) to (iii), Y represents a divalent linking group, and Ar represents an arylene group which may have a substituent. Y is preferably an alkylene group having 1 to 16 carbon atoms or a single bond. Methylene (—CH ₂ —) in an alkylene group is an ether bond (—O—), a thioether bond (—S—), an ester bond (—COO—), an amide bond (—CONR—; R is a hydrogen atom or an alkyl A bond which may be substituted with a methylene group, an ether bond or an ester bond is particularly preferable.
Among such divalent linking groups, particularly preferred specific examples are listed below.

  Particularly preferable examples of the monomer having a carboxylic acid group represented by the general formula (1) are shown below, but the present invention is not limited thereto.

-Monomers having sulfonic acid groups-
The monomer having a sulfonic acid group is not particularly limited as long as it is a polymerizable compound having a sulfonic acid group and a polymerizable double bond in its structure.
Preferable specific examples of the monomer having a sulfonic acid group include 3-sulfopropyl acrylate, 3-sulfopropyl methacrylate, and 4-styrene sulfonic acid.

-Monomer having a phosphonic acid group-
The monomer having a phosphonic acid group is not particularly limited as long as it is a polymerizable compound having a phosphonic acid group and a polymerizable double bond in its structure.
Preferable specific examples of the monomer having a phosphonic acid group include acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxypropyl methacrylate, and acid phosphoxypolyoxyethylene glycol monomethacrylate.

<Other monomers>
Specific examples of other monomers are given below, but the present invention is not limited thereto.

  (1) N- (4-hydroxyphenyl) acrylamide or N- (4-hydroxyphenyl) methacrylamide, o-, m- or p-hydroxystyrene, o- or m-bromo-p-hydroxysterene, o- or Acrylamides having an aromatic hydroxyl group such as m-chloro-p-hydroxyquinstyrene, o-, m- or p-hydroxyphenyl acrylate or methacrylate, methacrylamides, acrylic esters, methacrylic esters and hydroxystyrenes ;

  (2) N- (o-aminosulfonylphenyl) acrylamide, N- (m-aminosulfonylphenyl) acrylamide, N- (p-aminosulfonylphenyl) acrylamide, N- [1- (3-aminosulfonyl) naphthyl] acrylamide Acrylamides such as N- (2-aminosulfonylethyl) acrylamide, N- (o-aminosulfonylphenyl) methacrylamide, N- (m-aminosulfonylphenyl) methacrylamide, N- (p-aminosulfonylphenyl) methacryl Amides, methacrylamides such as N- [1- (3-aminosulfonyl) naphthyl] methacrylamide, N- (2-aminosulfonylethyl) methacrylamide, o-aminosulfonylphenyl acrylate, m-aminosulfonylphenyl Nyl acrylate, p-aminosulfonylphenyl acrylate, unsaturated sulfonamides such as acrylic esters such as 1- (3-aminosulfonylphenylnaphthyl) acrylate, o-aminosulfonylphenyl methacrylate, m-aminosulfonylphenyl methacrylate, p- Unsaturated sulphonamides such as methacrylic acid esters such as aminosulfonylphenyl metatalylate and 1- (3-aminosulfonylphenylnaphthyl) methacrylate;

(3) phenylsulfonylacrylamide, which may have a substituent such as tosylacrylamide, and phenylsulfonylmethacrylamide, which may have a substituent such as tosylmethacrylamide;
(4) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group, such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate;

  (5) Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, cyclohexyl acrylate, octyl acrylate, phenyl acrylate, benzyl acrylate, acrylic acid-2 -(Substituted) acrylic esters such as chloroethyl, 4-hydroxybutyl acrylate, glycidyl acrylate, N-dimethylaminoethyl acrylate;

  (6) Methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, octyl methacrylate, phenyl methacrylate, benzyl methacrylate, methacrylic acid-2 -(Substituted) methacrylate esters such as chloroethyl, 4-hydroxybutyl methacrylate, glycidyl methacrylate, N-dimethylaminoethyl methacrylate;

  (7) Acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N-ethyl acrylamide, N-ethyl methacrylamide, N-hexyl acrylamide, N-hexyl methacrylamide, N-cyclohexyl acrylamide, N- Cyclohexylmethacrylamide, N-hydroxyethylacrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N-phenylmethacrylamide, N-benzylacrylamide, N-benzylmethacrylamide, N-nitrophenylacrylamide, N-nitrophenylmethacrylamide Acrylamide or methacrylate such as N-ethyl-N-phenylacrylamide and N-ethyl-N-phenylmethacrylamide De;

  (8) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, phenyl vinyl ether;

(9) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate, vinyl benzoate;
(10) Styrenes such as styrene, α-methylstyrene, methylstyrene, chloromethylstyrene;
(11) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone;
(12) Olefin such as ethylene, propylene, isobutylene, butadiene, isoprene;

(13) N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile, etc .;
(14) Lactone group-containing monomers such as pantoyl lactone (meth) acrylate, α- (meth) acryloyl-γ-butyrolactone, β- (meth) acryloyl-γ-butyrolactone;
(15) Ethylene oxide group-containing monomers such as polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, and methoxypolyethylene glycol mono (meth) acrylate.

In the specific polymer, the content of other monomers described above is preferably 95 mol% or less, and more preferably 80 mol% or less.
Among the other monomers, it is more preferable to copolymerize (4) acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group, (5) acrylic acid esters, and (6) methacrylic acid esters.

Hereinafter, although the specific example (P-1 to P-13, P-15 ) of the specific polymer which concerns on this invention is given, this invention is not limited to these.

  As for content of the specific polymer in an intermediate | middle layer, 50-100 mass% is preferable with respect to the total solid which comprises an intermediate | middle layer, and 80-100 mass% is more preferable.

(Formation of intermediate layer)
The intermediate layer according to the present invention can be provided by applying a coating solution (intermediate layer forming coating solution) in which each component of the above-described intermediate layer is dissolved onto the support described later by various methods. Although there is no restriction | limiting in particular in the method of apply | coating an intermediate | middle layer, The following method is mentioned as a typical thing.
That is, (1) a solution in which the specific polymer in the present invention is dissolved in an organic solvent such as methanol, ethanol, methyl ethyl ketone, or a mixed solvent thereof, or a mixed solvent of these organic solvent and water is placed on a support. Application method that is applied and dried. Alternatively, (2) the support is immersed in a solution in which the specific polymer in the present invention is dissolved in an organic solvent such as methanol, ethanol, methyl ethyl ketone, or a mixed solvent thereof, or a mixed solvent of these organic solvent and water. However, after that, there may be mentioned a coating method in which an intermediate layer is provided by washing and drying with water or air.

  In the application method (1), a solution having a concentration of 0.005 to 10% by mass in total may be applied by various methods. As the coating means, any means such as bar coater coating, spin coating, spray coating, curtain coating, etc. may be used. In the coating method (2), the concentration of the solution is 0.005 to 20% by mass, preferably 0.01 to 10% by mass, and the immersion temperature is 0 to 70 ° C., preferably 5 to 60 ° C. The soaking time is 0.1 to 5 minutes, preferably 0.5 to 120 seconds.

The above intermediate layer forming coating solution includes basic substances such as ammonia, triethylamine, potassium hydroxide, inorganic acids such as hydrochloric acid, phosphoric acid, sulfuric acid, and nitric acid, organic sulfonic acids such as nitrobenzene sulfonic acid, naphthalene sulfonic acid, Adjust pH with various organic acidic substances such as organic phosphonic acid such as phenylphosphonic acid, organic carboxylic acid such as benzoic acid, coumaric acid and malic acid, organic chloride such as naphthalenesulfonyl chloride, benzenesulfonyl chloride, etc., pH = 0 12, More preferably, it can also be used in the range of pH = 0-6.
In addition, a substance that absorbs ultraviolet light, visible light, infrared light, or the like may be added to the coating solution for forming an intermediate layer in order to improve the tone reproducibility of the lithographic printing plate.

The total coating amount of the intermediate layer in the present invention after drying is appropriately 1 to 100 mg / m ² , and preferably ² to 70 mg / m ² .

[Photosensitive positive recording layer]
The photosensitive positive recording layer according to the present invention will be described. In the present invention, any photosensitive positive recording layer can be used as long as the solubility in an aqueous alkali solution is improved by exposure. For example, a conventional positive type in which the solubility in an alkaline aqueous solution is improved by ultraviolet exposure. Or a thermal positive type recording layer whose solubility in an alkaline aqueous solution is improved by infrared exposure. In the present invention, a thermal positive type recording layer is suitable. Hereinafter, a thermal positive type recording layer (hereinafter, referred to as “recording layer” as appropriate) will be described, but the present invention is limited to this. It is not a thing.
The thermal positive recording layer is preferably configured to contain (A) an alkali-soluble resin, (B) an infrared absorber, and (C) other components as necessary. Hereinafter, each component contained in the recording layer will be sequentially described.

[(A) Alkali-soluble resin]
The recording layer according to the present invention preferably contains an alkali-soluble resin. The alkali-soluble resin includes a homopolymer containing an acidic group in the main chain and / or side chain in the polymer, a copolymer thereof, or a mixture thereof.
Among these, those having an acidic group listed in the following (1) to (6) in the main chain and / or side chain of the polymer are preferable from the viewpoint of solubility in an alkaline developer and expression of dissolution inhibiting ability.

(1) Phenol group (-Ar-OH)
(2) sulfonamide group (-SO ₂ NH-R)
(3) Substituted sulfonamide acid group (hereinafter referred to as “active imide group”)
[—SO ₂ NHCOR, —SO ₂ NHSO ₂ R, —CONHSO ₂ R]
(4) Carboxylic acid group (—CO ₂ H)
(5) Sulfonic acid group (—SO ₃ H)
(6) Phosphate group (—OPO ₃ H ₂ )

  In the above (1) to (6), Ar represents a divalent aryl linking group which may have a substituent, and R represents a hydrogen atom or a hydrocarbon group which may have a substituent. .

  Among the alkali-soluble resins having an acidic group selected from the above (1) to (6), (1) an alkali-soluble resin having a phenol group, (2) a sulfonamide group, and (3) an active imide group is preferable. An alkali-soluble resin having (1) a phenol group or (2) a sulfonamide group is most preferable from the viewpoint of sufficiently ensuring solubility in an alkaline developer, development latitude, and film strength.

Examples of the alkali-soluble resin having an acidic group selected from the above (1) to (6) include the following.
(1) Examples of the alkali-soluble resin having a phenol group include a condensation polymer of phenol and formaldehyde, a condensation polymer of m-cresol and formaldehyde, a condensation polymer of p-cresol and formaldehyde, m− / p. A novolac resin such as a condensation polymer of mixed cresol and formaldehyde, a condensation polymer of phenol and cresol (m-, p- or m- / p-mixed) and formaldehyde, and pyrogallol and acetone. Can be mentioned. Furthermore, the copolymer which copolymerized the compound which has a phenol group in a side chain can also be mentioned. Alternatively, a copolymer obtained by copolymerizing a compound having a phenol group in the side chain can also be used.

  Examples of the compound having a phenol group include acrylamide, methacrylamide, acrylic acid ester, methacrylic acid ester, and hydroxystyrene having a phenol group.

  (2) As an alkali-soluble resin having a sulfonamide group, for example, a polymer composed of a minimum constituent unit derived from a compound having a sulfonamide group as a main constituent can be mentioned. Examples of the compound as described above include compounds having at least one sulfonamide group in which at least one hydrogen atom is bonded to a nitrogen atom and one or more polymerizable unsaturated groups in the molecule. Among these, low molecular compounds having an acryloyl group, an allyl group, or a vinyloxy group, and a substituted or monosubstituted aminosulfonyl group or a substituted sulfonylimino group in the molecule are preferable. For example, the following general formulas (i) to (v) The compound represented by these is mentioned.

In general formulas (i) to (v), X ¹ and X ² each independently represent —O— or —NR ⁷ . R ¹ and R ⁴ each independently represents a hydrogen atom or —CH ₃ . R ² , R ⁵ , R ⁹ , R ¹² and R ¹⁶ each independently represent a C 1-12 alkylene group, cycloalkylene group, arylene group or aralkylene group which may have a substituent. R ³ , R ⁷ and R ¹³ each independently represent a hydrogen atom, an optionally substituted alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group or an aralkyl group. R ⁶ and R ¹⁷ each independently represent a C 1-12 alkyl group, cycloalkyl group, aryl group, or aralkyl group that may have a substituent. R ⁸ , R ¹⁰ and R ¹⁴ each independently represent a hydrogen atom or —CH ₃ . R ¹¹ and R ¹⁵ each independently represent a C 1-12 alkylene group, cycloalkylene group, arylene group or aralkylene group which may have a single bond or a substituent. Y ¹ and Y ² each independently represent a single bond or CO.

  Among the compounds represented by the general formulas (i) to (v), in the lithographic printing plate precursor according to the invention, in particular, m-aminosulfonylphenyl methacrylate, N- (p-aminosulfonylphenyl) methacrylamide, N- ( p-Aminosulfonylphenyl) acrylamide and the like can be preferably used.

  (3) As an alkali-soluble resin having an active imide group, for example, a polymer composed of a minimum constituent unit derived from a compound having an active imide group as a main constituent can be mentioned. Examples of the compound as described above include compounds each having one or more active imide groups represented by the following structural formula and polymerizable unsaturated groups in the molecule.

  Specifically, N- (p-toluenesulfonyl) methacrylamide, N- (p-toluenesulfonyl) acrylamide and the like can be preferably used.

(4) As an alkali-soluble resin having a carboxylic acid group, for example, a minimum structural unit derived from a compound having at least one carboxylic acid group and polymerizable unsaturated group in the molecule is used as a main constituent component. A polymer can be mentioned.
(5) As an alkali-soluble resin having a sulfonic acid group, for example, a minimum structural unit derived from a compound having one or more sulfonic acid groups and polymerizable unsaturated groups in the molecule is used as a main structural unit. A polymer can be mentioned.
(6) As an alkali-soluble resin having a phosphate group, for example, a minimum structural unit derived from a compound having at least one phosphate group and a polymerizable unsaturated group in the molecule is used as a main constituent component. A polymer can be mentioned.

  The minimum structural unit having an acidic group selected from the above (1) to (6) that constitutes the alkali-soluble resin used in the recording layer is not necessarily limited to one kind, and is the minimum structural unit having the same acidic group. Two or more of these may be used, or two or more of the minimum structural units having different acidic groups may be copolymerized.

  The copolymer preferably contains 10 mol% or more of a compound having an acidic group selected from (1) to (6) to be copolymerized, and is contained in an amount of 20 mol% or more. Those are more preferred. If it is less than 10 mol%, the development latitude tends to be insufficiently improved.

  In the present invention, when the alkali-soluble resin is a copolymer, other compounds not containing the acidic groups (1) to (6) may be used as the copolymer component. Examples of other compounds not containing an acidic group of (1) to (6) include the compounds listed in the following (m1) to (m12), but are not limited thereto.

(M1) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
(M2) Alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, and glycidyl acrylate.
(M3) Alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, and glycidyl methacrylate.
(M4) Acrylamide, methacrylamide, N-methylol acrylamide, N-ethyl acrylamide, N-hexyl methacrylamide, N-cyclohexyl acrylamide, N-hydroxyethyl acrylamide, N-phenyl acrylamide, N-nitrophenyl acrylamide, N-ethyl- Acrylamide or methacrylamide such as N-phenylacrylamide.

(M5) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, and phenyl vinyl ether.
(M6) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.
(M7) Styrenes such as styrene, α-methylstyrene, methylstyrene, chloromethylstyrene.
(M8) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.
(M9) Olefins such as ethylene, propylene, isobutylene, butadiene and isoprene.
(M10) N-vinylpyrrolidone, acrylonitrile, methacrylonitrile and the like.
(M11) Unsaturated imides such as maleimide, N-acryloylacrylamide, N-acetylmethacrylamide, N-propionylmethacrylamide, N- (p-chlorobenzoyl) methacrylamide.
(M12) Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride and itaconic acid.

  The alkali-soluble resin preferably has a phenolic hydroxyl group from the viewpoint of excellent image-forming properties when exposed to infrared laser or the like. For example, a phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m- Preferred are novolak resins such as / p-mixed cresol formaldehyde resin and phenol / cresol (m-, p-, or m- / p-mixed) mixed formaldehyde resin and pyrogallol acetone resin.

  Further, as an alkali-soluble resin having a phenolic hydroxyl group, as described in US Pat. No. 4,123,279, a carbon number of 3 such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin is used. And a condensation polymer of phenol and formaldehyde having an alkyl group of ˜8 as a substituent.

  The alkali-soluble resin preferably has a weight average molecular weight of 500 or more from the viewpoint of image forming properties, and more preferably 1,000 to 700,000. Moreover, it is preferable that the number average molecular weight is 500 or more, and it is more preferable that it is 750-650,000. The dispersity (weight average molecular weight / number average molecular weight) is preferably 1.1-10.

Moreover, these alkali-soluble resins may be used alone or in combination of two or more.
In the case of combination, the number of carbon atoms such as a condensation polymer of t-butylphenol and formaldehyde or a condensation polymer of octylphenol and formaldehyde as described in US Pat. No. 4,123,279 is described. A polycondensation product of phenol and formaldehyde having 3 to 8 alkyl groups as substituents, a phenol having an electron-withdrawing group on the aromatic ring described in JP-A-2000-241972 previously filed by the present inventors You may use together alkali-soluble resin etc. which have a structure.

  As the alkali-soluble resin, strong hydrogen bonding occurs in the unexposed area, and in the exposed area, some hydrogen bonds are easily released, and the unexposed area with respect to the non-silicate developer, A polymer compound having a phenolic hydroxyl group is desirable because the image forming property is improved because the difference in developability between exposed portions is large. More preferred is a novolac resin.

  The total content of the alkali-soluble resin contained in the recording layer is preferably from 30 to 98% by mass, and preferably from 40 to 95% by mass, based on the total solid content of the recording layer, from the viewpoints of durability, sensitivity, and image formability. Is more preferable.

[(B) Infrared absorber]
The recording layer according to the present invention preferably contains an infrared absorber. As the infrared absorber, any substance that absorbs light energy radiation and generates heat can be used without any limitation in the absorption wavelength range, but from the viewpoint of compatibility with an easily available high-power laser. Is preferably an infrared-absorbing dye or pigment having an absorption maximum at a wavelength of 760 nm to 1200 nm.

  As the infrared absorbing dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, oxonol dyes And dyes such as diimonium dyes, aminium dyes, and croconium dyes.

  Examples of preferable dyes include cyanine dyes described in, for example, JP-A-58-125246, JP-A-59-84356, JP-A-59-202829, JP-A-60-78787, and the like. Methine dyes described in JP-A-58-173696, JP-A-58-181690, JP-A-58-194595, JP-A-58-112793, JP-A-58- Naphthoquinone dyes described in JP-A-224793, JP-A-59-48187, JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, etc. Examples include squarylium dyes described in JP-A-58-112792, and cyanine dyes described in British Patent 434,875.

  Further, near infrared absorption sensitizers described in US Pat. No. 5,156,938 are also preferably used, and substituted aryl benzoates described in US Pat. No. 3,881,924 are also preferably used. (Thio) pyrylium salt, trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051 and JP-A-58-220143 No. 59-41363, No. 59-84248, No. 59-84249, No. 59-146063, No. 59-146061, JP-A-59-216146. No. 5,13514, a cyanine dye described in US Pat. No. 4,283,475, a pentamethine thiopyrylium salt described in US Pat. No. 4,283,475, and the like. Pyrylium compounds Nos disclosed in Japanese 5-19702 are also preferably used.

  Moreover, as another example preferable as an infrared-absorbing dye, the near-infrared-absorbing dye described as Formula (I) and (II) in US Patent 4,756,993 can be mentioned.

Particularly preferred among these dyes are cyanine dyes, phthalocyanine dyes, oxonol dyes, squarylium dyes, pyrylium salts, thiopyrylium dyes, and nickel thiolate complexes. Furthermore, the dyes represented by the following general formulas (a) to (e) are preferable because they are excellent in photothermal conversion efficiency. Particularly, the cyanine dyes represented by the following general formula (a) are used in the recording layer according to the present invention. In this case, it is most preferable because it gives a high interaction with the alkali-soluble resin and is excellent in stability and economy.

In general formula (a), X ¹ represents a hydrogen atom, a halogen atom, —NPh ₂ , X ² -L ¹ or a group shown below. Here, X ² represents an oxygen atom or a sulfur atom, and L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or a carbon atom having 1 to 12 carbon atoms including a hetero atom. Indicates a hydrogen group. In addition, a hetero atom here shows N, S, O, a halogen atom, and Se. Xa ^- the Za described later ^- is defined as for, R ^a represents a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, substituted or unsubstituted amino group and a halogen atom.

R ¹ and R ² each independently represents a hydrocarbon group having 1 to 12 carbon atoms. From the storage stability of the lithographic printing plate precursor, R ¹ and R ² are preferably hydrocarbon groups having 2 or more carbon atoms, and R ¹ and R ² are bonded to each other to form a 5-membered ring. Alternatively, it is particularly preferable that a 6-membered ring is formed.

Ar ¹ and Ar ² may be the same or different and each represents an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Moreover, as a preferable substituent, a C12 or less hydrocarbon group, a halogen atom, and a C12 or less alkoxy group are mentioned. Y ¹ and Y ² may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ³ and R ⁴ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferred substituents include alkoxy groups having 12 or less carbon atoms, carboxyl groups, and sulfo groups. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred.
Za ⁻ represents a counter anion. However, Za ⁻ is not necessary when the cyanine dye represented by formula (a) has an anionic substituent in its structure and charge neutralization is not necessary. Preferred Za ⁻ is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a carboxylate ion, and a sulfonate ion because of the storage stability of the recording layer coating solution. From the viewpoint of solubility and solubility in a coating solution, halogen ions and organic acid ions such as carboxylate ions and sulfonate ions are preferable, sulfonate ions are more preferable, and aryl sulfonate ions are particularly preferable.

  Specific examples of the cyanine dye represented by the general formula (a) that can be suitably used in the present invention include those exemplified below, and paragraph numbers [0017] to [0019] of JP-A No. 2001-133969, Examples thereof include those described in paragraph numbers [0012] to [0038] of JP-A No. 2002-40638 and paragraph numbers [0012] to [0023] of JP-A No. 2002-23360.

In the general formula (b), L represents a methine chain having 7 or more conjugated carbon atoms, the methine chain may have a substituent, and the substituents may be bonded to each other to form a ring structure. Good. Zb ⁺ represents a counter cation. Preferred counter cations include ammonium, iodonium, sulfonium, phosphonium, pyridinium, alkali metal cations (Na ⁺ , K ⁺ , Li ⁺ ) and the like. R ^{9 to} R ¹⁴ and R ^{15 to} R ²⁰ each independently represent a hydrogen atom or a halogen atom, a cyano group, an alkyl group, an aryl group, an alkenyl group, an alkynyl group, a carbonyl group, a thio group, a sulfonyl group, a sulfinyl group, This represents a substituent selected from an oxy group or an amino group, or a combination of two or three of these, and may be bonded to each other to form a ring structure. Here, in general formula (b), those in which L represents a methine chain having 7 conjugated carbon atoms and those in which R ^{9 to} R ¹⁴ and R ^{15 to} R ²⁰ all represent hydrogen atoms are easily available. It is preferable from the viewpoint of effect.

  Specific examples of the dye represented by formula (b) that can be suitably used in the present invention include those exemplified below.

In general formula (c), Y ³ and Y ⁴ each represent an oxygen atom, a sulfur atom, a selenium atom, or a tellurium atom. M represents a methine chain having 5 or more conjugated carbon atoms. R ^{21 to} R ²⁴ and R ^{25 to} R ²⁸ may be the same or different, and are each a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an aryl group, an alkenyl group, an alkynyl group, a carbonyl group, a thiol group, Represents a group, a sulfonyl group, a sulfinyl group, an oxy group, or an amino group. Further, wherein Za ^- include a counter anion, Za in the general formula (a) ^- it is synonymous.

  In the present invention, specific examples of the dye represented by formula (c) that can be suitably used include those exemplified below.

In general formula (d), R ²⁹ to R ³¹ each independently represent a hydrogen atom, an alkyl group, or an aryl group. R ³³ and R ³⁴ each independently represents an alkyl group, a substituted oxy group, or a halogen atom. n and m each independently represents an integer of 0 to 4. R ²⁹ and R ³⁰ , or R ³¹ and R ³² may be bonded to form a ring. R ²⁹ and / or R ³⁰ may be combined with R ³³ and R ³¹ and / or R ³² may be combined with R ³⁴ to form a ring, and when there are a plurality of R ³³ or R ³⁴ is R ³³ or between R ³⁴ together may be bonded to each other to form a ring. X ² and X ³ each independently represent a hydrogen atom, an alkyl group, or an aryl group, and at least one of X ² and X ³ represents a hydrogen atom or an alkyl group. Q is a trimethine group or a pentamethine group which may have a substituent, and may form a ring structure together with a divalent organic group. Zc ⁻ represents a counter anion and has the same meaning as Za ⁻ in the general formula (a).

  In the present invention, specific examples of the dye represented by the general formula (d) that can be suitably used include those exemplified below.

In the general formula (e), R ^{35 to} R ⁵⁰ each independently represent a hydrogen atom, a halogen atom, a cyano group, an alkyl group, an aryl group, an alkenyl group, an alkynyl group, a hydroxyl group, a carbonyl group, a thio group, a sulfonyl group, When a sulfinyl group, an oxy group, an amino group, or an onium salt structure is shown and a substituent can be introduced, it may have a substituent. M represents two hydrogen atoms or metal atoms, a halometal group, and an oxymetal group, and the metal atoms contained therein include IA, IIA, IIIB, IVB group atoms of the periodic table, first, second, second Three-period transition metals and lanthanoid elements can be mentioned, among which copper, magnesium, iron, zinc, cobalt, aluminum, titanium, and vanadium are preferable.

  In the present invention, specific examples of the dye represented by formula (e) that can be suitably used include those exemplified below.

  Examples of pigments used as infrared absorbers in the present invention include commercially available pigments and Color Index (CI) manual, “Latest Pigment Handbook” (edited by the Japan Pigment Technology Association, published in 1977), “Latest Pigment Applied Technology”. (CMC Publishing, published in 1986) and “Printing Ink Technology”, published by CMC Publishing, published in 1984).

  Examples of the pigment include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bonded dyes. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments In addition, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used. Among these pigments, carbon black is preferable.

  These pigments may be used without surface treatment, or may be used after surface treatment. The surface treatment method includes a method of surface coating with a resin or wax, a method of attaching a surfactant, a method of bonding a reactive substance (eg, silane coupling agent, epoxy compound, polyisocyanate, etc.) to the pigment surface, etc. Can be considered. The above-mentioned surface treatment methods are described in “Characteristics and Applications of Metal Soap” (Shobobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). Yes.

  The particle diameter of the pigment is preferably in the range of 0.01 μm to 10 μm from the viewpoints of stability and uniformity of the recording layer when the pigment dispersion is used as a recording layer coating liquid for a lithographic printing plate precursor. More preferably in the range of 0.05 μm to 1 μm, particularly preferably in the range of 0.1 μm to 1 μm. When the particle size of the pigment is less than 0.01 μm, it is not preferable in terms of stability when the pigment dispersion is used as a recording layer coating liquid for a lithographic printing plate precursor, and when it exceeds 10 μm, the recording layer is uniform. It is not preferable in terms of sex.

  As a method for dispersing the pigment, a known dispersion technique used in ink production, toner production, or the like can be used. Examples of the disperser include an ultrasonic disperser, a sand mill, an attritor, a pearl mill, a super mill, a ball mill, an impeller, a disperser, a KD mill, a colloid mill, a dynatron, a three-roll mill, and a pressure kneader. Details are described in "Latest Pigment Applied Technology" (CMC Publishing, 1986).

  These pigments or dyes are 0.01 to 50% by mass, preferably 0.1 to 10% by mass, based on the total solid content constituting the recording layer, from the viewpoints of sensitivity, recording layer uniformity, and printing durability. It is. In the case of a dye, it is particularly preferably 0.5 to 10% by mass, and in the case of a pigment, it is particularly preferably 0.1 to 10% by mass.

[(C) Other ingredients]
Various additives can be further added to the recording layer according to the present invention as necessary. In particular, a substance (decomposable solvent inhibitor) that is thermally decomposable, such as an onium salt, an o-quinonediazide compound, and a sulfonic acid alkyl ester, and substantially reduces the solubility of the alkali-soluble resin when not decomposed may be used in combination. It is preferable from the viewpoint of improving dissolution inhibition of the image area in the developer. As the decomposable dissolution inhibitor, onium salts such as diazonium salts, iodonium salts, sulfonium salts, ammonium salts, and o-quinonediazide compounds are preferred, diazonium salts, iodonium salts, onium salts of sulfonium salts are more preferred, and diazonium salts are preferred. It is particularly preferable to add it as a thermally decomposable dissolution inhibitor.

Suitable examples of the onium salt used in the present invention include S.P. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. Bal et al, Polymer, 21, 423 (1980), diazonium salts described in JP-A-5-158230, U.S. Pat. Nos. 4,069,055, 4,069,056, and JP-A-3-140140. Ammonium salts described in the specification of C. Necker et al, Macromolecules, 17, 2468 (1984), C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), U.S. Pat. Nos. 4,069,055 and 4,069,056; V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), Chem. & Eng. News, Nov. 28, p31 (1988), European Patent No. 104,143, US Pat. No. 5,041,358, US Pat. No. 4,491,628, Japanese Patent Laid-Open No. 2-150848, Japanese Patent Laid-Open No. Iodonium salts described in JP-A-2-296514, J. Org. V. Crivello et al, Polymer J. et al. 17, 73 (1985), J. Am. V. Crivello et al. J. et al. Org. Chem. 43, 3055 (1978); R. Watt et al, J.A. Polymer Sci. , Polymer Chem. Ed. , 22, 1789 (1984), J. Am. V. Crivello et al, Polymer Bull. 14, 279 (1985), J. Am. V. Crivello et al, Macromolecules, 14 (5), 1141 (1981), J. MoI. V. Crivello et al, J.A. Polymer Sci. , Polymer Chem. Ed. 17, 2877 (1979), European Patent Nos. 370,693, 233,567, 297,443, 297,442, U.S. Pat. No. 4,933,377. No. 3,902,114, No. 5,041,358, No. 4,491,628, No. 4,760,013, No. 4,734,444 No. 2,833,827, German Patent 2,904,626, 3,604,580, 3,604,581 Salt, J.M. V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), J. MoI. V. Crivello et al, J.A. Polymer Sci. , Polymer Chem. Ed. , 17, 1047 (1979), a selenonium salt described in C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988).
Among these onium salts, diazonium salts are particularly preferable from the viewpoints of dissolution inhibiting ability and thermal decomposability. In particular, the diazonium salt represented by the general formula (I) described in JP-A No. 5-158230 and the diazonium salt represented by the general formula (1) described in JP-A No. 11-143064 are preferable. The diazonium salt represented by the general formula (1) described in JP-A-11-143064 having a small absorption wavelength is most preferable.

  The counter ion of the onium salt includes tetrafluoroboric acid, hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid, 5-nitro-o-toluenesulfonic acid, 5-sulfosalicylic acid, 2,5-dimethylbenzenesulfonic acid, 2,4,6-trimethylbenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 3-bromobenzenesulfonic acid, 2-fluorocaprylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, 1-naphthol-5-sulfone Examples include acid, 2-methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid, and paratoluenesulfonic acid. Of these, particularly preferred are alkyl aromatic sulfonic acids such as hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid and 2,5-dimethylbenzenesulfonic acid.

  The o-quinonediazide compound used in the present invention is a compound having at least one o-quinonediazide group, which increases alkali solubility by thermal decomposition, and compounds having various structures can be used. That is, o-quinonediazide helps the solubility of the sensitive material system by both the effect of losing the ability to suppress the dissolution of the binder due to thermal decomposition and the change of o-quinonediazide itself into an alkali-soluble substance. Examples of the o-quinonediazide compound used in the present invention include J. The compounds described in pages 339 to 352 of “Light-sensitive systems” by John Coley (John Wiley & Sons. Inc.) can be used, and in particular, o-quinonediazide reacted with various aromatic polyhydroxy compounds or aromatic amino compounds. The sulfonic acid esters or sulfonic acid amides are preferred. Further, benzoquinone (1,2) -diazidosulfonic acid chloride or naphthoquinone- (1,2) -diazide-5-sulfonic acid chloride and pyrogallol-acetone resin as described in JP-B-43-28403 Esters of benzoquinone- (1,2) -diazide sulfonic acid chloride or naphthoquinone- (1,2) described in US Pat. Nos. 3,046,120 and 3,188,210. An ester of) -diazide-5-sulfonic acid chloride with a phenol-formaldehyde resin is also preferably used.

  Further, an ester of naphthoquinone- (1,2) -diazido-4-sulfonic acid chloride and phenol formaldehyde resin or cresol-formaldehyde resin, naphthoquinone- (1,2) -diazido-4-sulfonic acid chloride and pyrogallol-acetone resin Similarly, the esters are also preferably used. Other useful o-quinonediazide compounds are reported and known in numerous patents. For example, JP-A-47-5303, JP-A-48-63802, JP-A-48-63803, JP-A-48-96575, JP-A-49-38701, JP-A-48-13354, Japanese Patent Publication Nos. 41-11222, 45-9610, 49-17482, U.S. Pat. Nos. 2,797,213, 3,454,400, and 3,544 No. 323, No. 3,573,917, No. 3,674,495, No. 3,785,825, British Patent No. 1,227,602, No. 1,251,345, No. No. 1,267,005, No. 1,329,888, No. 1,330,932, German Patent No. 854,890 and the like. .

  The addition amount of the onium salt and / or o-quinonediazide compound which is a degradable dissolution inhibitor is preferably 0.1 to 10% by mass, more preferably 0.00%, based on the total solid content of the recording layer in the invention. It is 1-5 mass%, Most preferably, it is the range of 0.2-2 mass%. These compounds can be used alone, but may be used as a mixture of several kinds.

  The addition amount of the degradable solvent inhibitor other than the o-quinonediazide compound is preferably 0 to 5% by mass, more preferably 0 to 2% by mass, and particularly preferably 0.1 to 1.5% by mass. The additive and binder used in the present invention are preferably contained in the same layer.

  Further, a dissolution inhibitor having no decomposability may be used in combination, and preferred dissolution inhibitors include sulfonate esters, phosphate esters, and aromatic carboxylic acids described in detail in JP-A-10-268512. Esters, aromatic disulfones, carboxylic anhydrides, aromatic ketones, aromatic aldehydes, aromatic amines, aromatic ethers, etc., as well as lactone skeletons described in detail in JP-A-11-190903, N, N- Examples thereof include an acid color-forming dye having a diarylamide skeleton and a diarylmethylimino skeleton, which also serves as a colorant, and nonionic surfactants described in detail in JP-A No. 2000-105454.

Further, in order to enhance image discrimination (hydrophobic / hydrophilic discrimination) and to enhance resistance to scratches on the surface, carbon described in JP-A-2000-187318 is used. A polymer containing a (meth) acrylate monomer having 2 or 3 perfluoroalkyl groups of 3 to 20 as a polymerization component can be used in combination. As the addition amount of such a compound, when used for the recording layer of the lithographic printing plate of the invention, it is preferably from 0.1 to 10% by mass, more preferably from 0.5 to 10%, based on the total solid content of the recording layer. 5% by mass.
In the present invention, for the purpose of imparting resistance to scratches, a compound that lowers the static friction coefficient of the surface can also be added. Specific examples include esters of long-chain alkyl carboxylic acids as used in US Pat. No. 6,117,913. The amount of such a compound added is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, based on the total solid content of the recording layer of the lithographic printing plate precursor according to the invention.
Further, the present invention may contain a compound having a low molecular weight acidic group as required. Examples of acidic groups include sulfonic acid groups, carboxylic acid groups, and phosphoric acid groups. Of these, compounds having a sulfonic acid group are preferred. Specific examples include aromatic sulfonic acids such as p-toluenesulfonic acid and naphthalenesulfonic acid, and aliphatic sulfonic acids.

  In addition, for the purpose of further improving sensitivity, cyclic acid anhydrides, phenols, and organic acids can be used in combination. Examples of cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 3,6-endooxy-Δ4-tetrahydrophthalic anhydride described in US Pat. No. 4,115,128, Tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used. As phenols, bisphenol A, p-nitrophenol, p-ethoxyphenol, 2,4,4′-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4-hydroxybenzophenone, 4,4 ′, 4 “-Trihydroxytriphenylmethane, 4,4 ′, 3”, 4 ”-tetrahydroxy-3,5,3 ′, 5′-tetramethyltriphenylmethane and the like. There are sulfonic acids, sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphoric acid esters, carboxylic acids, and the like, which are described in Japanese Laid-Open Patent Publication No. 60-88942 and Japanese Patent Application Laid-Open No. 2-96755. , P-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethyl sulfate Phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid, p-toluic acid, 3,4-dimethoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene-1, 2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, ascorbic acid, etc. When added to the recording layer of the lithographic printing plate precursor of the above cyclic acid anhydrides, phenols and organic acids, the recording layer The proportion of the content is preferably 0.05 to 20% by mass, more preferably 0.1 to 15% by mass, and particularly preferably 0.1 to 10% by mass.

  Further, the recording layer according to the present invention has a nonionic surfactant as described in JP-A Nos. 62-251740 and 3-208514 in order to broaden the processing stability against development conditions. , Amphoteric surfactants as described in JP-A-59-121044 and JP-A-4-13149, siloxane-based compounds as described in EP950517, JP-A-11-288093 Fluorine-containing monomer copolymers as described can be added.

Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether and the like. Specific examples of the double-sided activator include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine and N-tetradecyl-N, N-betaine. Type (for example, trade name “Amorgen K” manufactured by Daiichi Kogyo Co., Ltd.).
The siloxane compound is preferably a block copolymer of dimethylsiloxane and polyalkylene oxide. Specific examples include DBE-224, DBE-621, DBE-712, DBP-732, DBP-534, manufactured by Chisso Corporation. And polyalkylene oxide-modified silicones such as Tego Glide 100 manufactured by Tego, Germany.
The proportion of the nonionic surfactant and the amphoteric surfactant in the recording layer is preferably 0.05 to 15% by mass, more preferably 0.1 to 5% by mass.

To the recording layer according to the present invention, a print-out agent for obtaining a visible image immediately after heating by exposure, or a dye or pigment as an image colorant can be added.
Typical examples of the printing-out agent include a combination of a compound that releases an acid by heating by exposure (photoacid releasing agent) and an organic dye that can form a salt. Specifically, combinations of o-naphthoquinonediazide-4-sulfonic acid halides and salt-forming organic dyes described in JP-A-50-36209 and JP-A-53-8128, 36223, 54-74728, 60-3626, 61-143748, 61-151644 and 63-58440, and trihalomethyl compounds and salt-forming organic dyes Can be mentioned. Such trihalomethyl compounds include oxazole compounds and triazine compounds, both of which have excellent temporal stability and give clear printout images.

  As the image colorant, other dyes can be used in addition to the above-mentioned salt-forming organic dyes. Examples of suitable dyes including salt-forming organic dyes include oil-soluble dyes and basic dyes. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (oriental chemical industry) Manufactured by Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI522015), and the like. The dyes described in JP-A-62-293247 are particularly preferred. These dyes can be added in a proportion of 0.01 to 10% by mass, preferably 0.1 to 3% by mass, based on the total solid content of the recording layer. Furthermore, a plasticizer is added to the present invention as needed to impart flexibility and the like of the coating film. For example, butylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, acrylic acid or methacrylic acid These oligomers and polymers are used.

  In addition to these, epoxy compounds, vinyl ethers, and further, phenol compounds having a hydroxymethyl group, phenol compounds having an alkoxymethyl group described in JP-A-8-276558, A crosslinkable compound having an alkali dissolution inhibiting action described in JP-A-11-160860 proposed in JP-A-11-160860 can be appropriately added depending on the purpose.

[Formation of recording layer]
The recording layer according to the present invention can be formed by dissolving each component constituting the above-described recording layer in a solvent and coating the solution on the intermediate layer.
Solvents used here include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxy Examples include ethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyrolactone, and toluene. It is not limited. These solvents are used alone or in combination.
The concentration of the above components (total solid content including additives) in the solvent is preferably 1 to 50% by mass.

The coating amount (solid content) obtained after coating and drying varies depending on the use, but is generally preferably 0.5 to 5.0 g / m ² . As the coating amount decreases, the apparent sensitivity increases, but the film properties of the photosensitive film (recording layer) decrease.
Various methods can be used as the coating method, and examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.
In the recording layer of the present invention, a surfactant for improving the coating property, for example, a fluorine-based surfactant described in JP-A No. 62-170950 can be added. A preferable addition amount is 0.01 to 1% by mass, more preferably 0.05 to 0.5% by mass, based on the total solid content of the recording layer.

[Configuration of recording layer]
The recording layer according to the present invention may have a multilayer structure. For example, a resin layer made of an alkali-soluble polymer is used as the lower layer (support side), the recording layer described above is provided as the upper layer, and a two-layer structure is provided. Can do.
As a result, the recording layer (upper layer) whose solubility in an alkaline developer is lowered by exposure is provided on the exposed surface or in the vicinity thereof, whereby the sensitivity to the infrared laser is improved, and the support and the recording layer Since this resin layer (lower layer) exists between them and functions as a heat insulating layer, the heat generated by the infrared laser exposure is not diffused to the support, and the sensitivity can be increased because it is used efficiently.
In the exposed area, the recording layer (upper layer) that has become impermeable to the alkaline developer functions as a protective layer for the resin layer (lower layer). It is considered that an image excellent in nation is formed and stability over time is secured. Further, in the unexposed area, the uncured binder component is quickly dissolved and dispersed in the developer, and the resin layer (lower layer) existing adjacent to the support is made of an alkali-soluble polymer. Therefore, the solubility in the developer is good. For example, even when a developer with reduced activity is used, it dissolves quickly without the formation of a residual film, so that it is considered that the developability is excellent.

[Support]
As the support used in the lithographic printing plate precursor according to the present invention, a dimensionally stable plate-like material is used. For example, paper, paper laminated with plastic (for example, polyethylene, polypropylene, polystyrene, etc.), Metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate , Polyvinyl acetal, etc.), paper laminated with a metal as described above, or vapor-deposited paper, or plastic film.

  As the support according to the present invention, a polyester film or an aluminum plate is preferable, and among them, an aluminum plate that has good dimensional stability and is relatively inexpensive is particularly preferable. A suitable aluminum plate is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of different elements, and may be a plastic film on which aluminum is laminated or vapor-deposited. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is at most 10% by mass. Particularly suitable aluminum in the present invention is pure aluminum, but completely pure aluminum is difficult to produce in the refining technique, and may contain slightly different elements. Thus, the composition of the aluminum plate applied to the present invention is not specified, and an aluminum plate made of a publicly known material can be appropriately used. The thickness of the aluminum plate used in the present invention is about 0.1 mm to 0.6 mm, preferably 0.15 mm to 0.4 mm, and particularly preferably 0.2 mm to 0.3 mm.

Prior to roughening the aluminum plate, a degreasing treatment with, for example, a surfactant, an organic solvent, or an alkaline aqueous solution for removing rolling oil on the surface is performed as desired.
The surface roughening treatment of the aluminum plate is performed by various methods. For example, a method of mechanically roughening, a method of electrochemically dissolving and roughening a surface, and a method of selectively dissolving a surface chemically. This is done by the method of As the mechanical method, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used. Further, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in hydrochloric acid or nitric acid electrolyte. Further, as disclosed in JP-A-54-63902, a method in which both are combined can also be used.

The roughened aluminum plate is subjected to alkali etching treatment and neutralization treatment as necessary, and then subjected to anodization treatment if desired in order to enhance the water retention and wear resistance of the surface. As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, phosphoric acid, oxalic acid, chromic acid, or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.
The treatment conditions for anodization vary depending on the electrolyte used and cannot be specified. However, in general, the concentration of the electrolyte is 1 to 80% by mass, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / dm. ^{2. A} voltage of 1 to 100 V and an electrolysis time of 10 seconds to 5 minutes are suitable.
When the amount of the anodic oxide film is less than 1.0 g / m ² , the printing durability is insufficient, or the non-image portion of the lithographic printing plate is easily damaged, and the ink adheres to the damaged portion during printing. In some cases, so-called “scratch dirt” is likely to occur.

After the anodizing treatment, the aluminum surface is subjected to a hydrophilic treatment if necessary. As the hydrophilization treatment used in the present invention, each specification of US Pat. Nos. 2,714,066, 3,181,461, 3,280,734 and 3,902,734 is disclosed. There is an alkali metal silicate (for example, aqueous sodium silicate) method as disclosed in US Pat. In this method, the support is immersed in an aqueous sodium silicate solution or electrolytically treated. In addition, potassium fluoride zirconate disclosed in Japanese Patent Publication No. 36-22063 and U.S. Pat. Nos. 3,276,868, 4,153,461, and 4,689,272 For example, a method of treating with polyvinylphosphonic acid as disclosed in the literature is used.
As a particularly preferable support treatment, an aluminum plate is subjected to mechanical surface roughening treatment, alkali etching treatment, desmutting treatment with acid, electrochemical surface roughening treatment using an electrolytic solution containing nitric acid, and an aqueous solution containing hydrochloric acid. It is preferable to sequentially perform an electrochemical surface roughening treatment using. A support subjected to such treatment has a very high surface area.

  The reason why the intermediate layer according to the present invention exhibits a more preferable effect on the support subjected to the above treatment is not well understood, but the intermediate layer according to the present invention is a substrate even for a support having a very high surface area. It is considered that the surface of the substrate can be sufficiently covered by the effect of interacting with the substrate, so that the adhesion between the recording layer (photosensitive layer) and the support can be further improved, and good non-image area staining can be achieved.

  The lithographic printing plate precursor of the present invention is converted into a lithographic printing plate by various processing methods corresponding to the recording layer. The developer is substantially free of alkali metal silicate as follows. A lithographic printing plate is preferred depending on the developing method. That is, the lithographic printing plate precursor according to the invention is preferably a lithographic printing plate precursor to be treated with a developer containing substantially no alkali metal silicate. This method is described in detail in JP-A No. 11-109637, and in the present invention, the contents described in the publication can be used.

The lithographic printing plate precursor produced as described above is usually subjected to image exposure and development processing. The light source used for image exposure can be appropriately selected according to the photosensitivity of the recording layer. Specifically, examples of the active light source include a mercury lamp, a metal halide lamp, a xenon lamp, and a chemical lamp. Examples of the laser beam include a helium / neon laser (He-Ne laser), an argon laser, a krypton laser, a helium / cadmium laser, a KrF excimer laser, a semiconductor laser, a solid laser, a YAG laser, and a YAG-SHG laser. It is done.
In particular, if the recording layer is a thermal positive type, a light source having an emission wavelength from the near infrared to the infrared region is preferable, and a solid laser or a semiconductor laser is particularly preferable.

As the developer and replenisher for the lithographic printing plate precursor according to the invention, conventionally known alkaline aqueous solutions can be used.
For example, sodium silicate, potassium, tribasic sodium phosphate, potassium, ammonium, dibasic sodium phosphate, potassium, ammonium, sodium carbonate, potassium, ammonium, sodium bicarbonate, potassium, Examples include inorganic alkali salts such as ammonium, sodium borate, potassium, ammonium, sodium hydroxide, ammonium, potassium, and lithium. In addition, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, Organic alkali agents such as ethyleneimine, ethylenediamine, and pyridine are also used. These alkali agents are used alone or in combination of two or more.
Among these alkali agents, particularly preferred developers are aqueous silicate solutions such as sodium silicate and potassium silicate. The reason is that the developability can be adjusted by the ratio and concentration of silicon oxide SiO ₂ and alkali metal oxide M ₂ O, which are silicate components. For example, Japanese Patent Application Laid-Open No. 54-62004, Alkali metal silicates as described in JP-B-57-7427 are effectively used.

Furthermore, when developing using an automatic developing machine, an aqueous solution (replenisher) having a higher alkali strength than that of the developer is added to the developer so that the developer in the developer tank is not changed for a long time. It is known that the PS version can be processed. This replenishment method is also preferably applied in the present invention. Various surfactants and organic solvents can be added to the developer and replenisher as necessary for the purpose of promoting and suppressing developability, dispersing development residue, and improving ink affinity of the printing plate image area.
Preferred surfactants include anionic, cationic, nonionic and amphoteric surfactants. If necessary, the developer and replenisher may contain reducing agents such as hydroquinone, resorcin, sulfurous acid, bisulfite, and other inorganic acids such as sodium salts and potassium salts, organic carboxylic acids, antifoaming agents, and hard water softeners. It can also be added.

  The printing plate developed using the developer and the replenisher is post-treated with water-washing water, a rinsing solution containing a surfactant and the like, a desensitizing solution containing gum arabic and starch derivatives. As the post-process applied to the present invention, these processes can be used in various combinations.

  In recent years, automatic developing machines for printing plates have been widely used in the plate making and printing industries in order to rationalize and standardize plate making operations. This automatic developing machine is generally composed of a developing unit and a post-processing unit, and includes an apparatus for transporting the printing plate, each processing liquid tank and a spray device, and each pumped up by a pump while transporting the exposed printing plate horizontally. The processing liquid is sprayed from the spray nozzle and developed. In addition, recently, a method is also known in which a printing plate is dipped and conveyed by a submerged guide roll or the like in a processing liquid tank filled with the processing liquid. In such automatic processing, each processing solution can be processed while being supplemented with a replenisher according to the processing amount, operating time, and the like. In addition, a so-called disposable processing method in which processing is performed with a substantially unused processing solution can also be applied.

  In the lithographic printing plate precursor according to the invention, image portions unnecessary for the lithographic printing plate obtained by image exposure, development, washing and / or rinsing and / or gumming (for example, film edge marks of the original film, etc.) ), Unnecessary image portions are erased. Such erasing is preferably performed by applying an erasing solution as described in, for example, Japanese Patent Publication No. 2-13293 to an unnecessary image portion, leaving it for a predetermined time, and then washing with water. As described in JP-A-59-174842, a method of developing after irradiating an unnecessary image portion with an actinic ray guided by an optical fiber can also be used.

The lithographic printing plate obtained as described above can be subjected to a printing process after applying a desensitized gum if desired. However, if it is desired to obtain a lithographic printing plate with a higher printing durability, it is desired. The burning process is performed.
In the case of burning a lithographic printing plate, before burning, an adjustment as described in JP-B-61-2518, JP-A-55-28062, JP-A-62-31859, JP-A-61-159655 is used. It is preferable to treat with a surface liquid.
As its method, with a sponge or absorbent cotton soaked with the surface-adjusting liquid, it is applied onto a lithographic printing plate, or a method in which the printing plate is immersed and applied in a vat filled with the surface-adjusting liquid, Application by an automatic coater is applied. Further, it is more preferable to make the coating amount uniform with a squeegee or a squeegee roller after coating.

In general, the amount of surface-adjusting solution applied is suitably 0.03 to 0.8 g / m ² (dry mass). The lithographic printing plate coated with the surface-adjusting liquid is dried if necessary and then heated to a high temperature with a burning processor (for example, burning processor “BP-1300” sold by Fuji Photo Film Co., Ltd.). Is done. In this case, the heating temperature and time are in the range of 180 to 300 ° C. and preferably in the range of 1 to 20 minutes, although depending on the type of components forming the image.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

[Synthesis of Monomer (M-1)]
Monomer (M-1) was synthesized as follows.
In a 1 L beaker, 20.0 g (78.8 mmol) of vinylbenzyltriethylammonium chloride and 700 ml of H ₂ O were dissolved while stirring at room temperature, to which 21.13 g (78.8 mmol) of 5-sulfoisophthalic acid sodium salt was added. Was added and stirred for 30 minutes. The precipitated crystals were filtered, washed with water, and dried to obtain 25.46 g (yield 69.7%) of monomer (M-1). The structure of the monomer (M-1) is shown below.

[Synthesis of Monomer (M-2)]
The monomer (M-2) was synthesized as follows.
In a 1 L beaker, 30.0 g (124.8 mmol) of 4-sulfobenzoic acid potassium salt and 650 ml of H ₂ O were dissolved while stirring at room temperature, and 31.69 g (124.8 mmol) of vinylbenzyltriethylammonium chloride was added thereto. ) Was added and stirred for 30 minutes. The precipitated crystals were filtered and dried to obtain 31.75 g (yield 65.3%) of monomer (M-2). The structure of the monomer (M-2) is shown below.

[Synthesis of Specific Polymer (P-1)]
The specific polymer (P-1) was synthesized as follows.
In a 300 ml three-necked flask to which 15.6 g of MeOH was added, in a nitrogen atmosphere at 70 ° C., 6.95 g (15.0 mmol) of the synthetic monomer (M-1), 12.59 g (85.0 mmol) of paravinylbenzoic acid, V − A solution of 601 1.151 g (5.0 mmol) and MeOH 62.5 g was added dropwise over 2 hours, and the reaction was further continued for 4 hours. The reaction solution was reprecipitated with water, filtered and dried to obtain 15.37 g of the specific polymer (P-1). It was 13,000 when the weight average molecular weight (polystyrene standard) of the specific polymer (P-1) was measured by the gel permeation chromatography.

[Synthesis of Specific Polymer (P-2)]
The specific polymer (P-2) was synthesized as follows.
In a 300 ml three-necked flask to which 15.1 g of MeOH was added under a nitrogen atmosphere at 70 ° C., 6.29 g (15.0 mmol) of the above synthetic monomer (M-2), 12.59 g (85.0 mmol) of paravinylbenzoic acid, V − A solution of 601 1.151 g (5.0 mmol) and MeOH 60.4 g was added dropwise over 2 hours, and the reaction was further continued for 4 hours. The reaction solution was reprecipitated with water, filtered and dried to obtain 15.57 g of the specific polymer (P-2). The weight average molecular weight (polystyrene standard) of the specific polymer (P-2) was measured by gel permeation chromatography and found to be 10,000.

[Synthesis of Specific Polymer (P-5)]
The specific polymer (P-5) was synthesized as follows.
In a 200 ml three-necked flask to which 6.7 g of DMAc was added, under a nitrogen atmosphere at 75 ° C., 4.17 g (9.0 mmol) of the synthetic monomer (M-1), 3.0 g (12.0 mmol) of vinylbenzyliminodiacetic acid, A solution of 1.17 g (9.0 mmol) of hydroxyethyl methacrylate, 0.460 g (2.0 mmol) of V-601 and 26.7 g of DMAc was added dropwise over 2 hours, and the mixture was further reacted for 4 hours. The reaction solution was reprecipitated with acetone, filtered and dried to obtain 6.76 g of the specific polymer (P-5). It was 64,000 when the weight average molecular weight (polystyrene standard) of the specific polymer (P-5) was measured by the gel permeation chromatography.

[Synthesis of Specific Polymer (P-6)]
The specific polymer (P-6) was synthesized as follows.
In a 200 ml three-necked flask to which 10.20 g of DMAc was added, in a nitrogen atmosphere at 75 ° C., 3.78 g (9.0 mmol) of the synthetic monomer (M-2), 3.0 g (12.0 mmol) of vinylbenzyliminodiacetic acid, A solution of 1.17 g (9.0 mmol) of hydroxyethyl methacrylate, 0.460 g (2.0 mmol) of V-601 and 24.6 g of DMAc was added dropwise over 2 hours, and the mixture was further reacted for 4 hours. The reaction solution was reprecipitated with acetone, filtered and dried to obtain 6.74 g of the specific polymer (P-6). It was 59,000 when the weight average molecular weight (polystyrene standard) of the specific polymer (P-6) was measured by the gel permeation chromatography.

[Synthesis of Specific Polymer (P-11)]
The specific polymer (P-11) was synthesized as follows.
In a 200 ml three-necked flask to which 6.5 g of DMAc was added, under a nitrogen atmosphere at 75 ° C., 4.17 g (9.0 mmol) of the synthetic monomer (M-1), 3.0 g (12.0 mmol) of vinylbenzyliminodiacetic acid, A solution of 0.90 g (9.0 mmol) of methyl methacrylate, 0.460 g (2.0 mmol) of V-601 and 25.8 g of DMAc was added dropwise over 2 hours, and the mixture was further reacted for 4 hours. The reaction solution was reprecipitated with acetone, filtered and dried to obtain 6.29 g of the specific polymer (P-11). It was 54,000 when the weight average molecular weight (polystyrene standard) of the specific polymer (P-11) was measured by the gel permeation chromatography.

[Synthesis of Specific Polymer (P-12)]
The specific polymer (P-12) was synthesized as follows.
In a 200 ml three-necked flask to which 6.1 g of DMAc was added, under a nitrogen atmosphere at 75 ° C., 3.78 g (9.0 mmol) of the synthetic monomer (M-2), 3.0 g (12.0 mmol) of vinylbenzyliminodiacetic acid, A solution of 0.90 g (9.0 mmol) of methyl methacrylate, 0.460 g (2.0 mmol) of V-601 and 24.6 g of DMAc was added dropwise over 2 hours, and the mixture was further reacted for 4 hours. The reaction solution was reprecipitated with acetone, filtered and dried to obtain 5.81 g of the specific polymer (P-12). It was 48,000 when the weight average molecular weight (polystyrene standard) of the specific polymer (P-12) was measured by the gel permeation chromatography.

[Examples 1 to 8]
(Production of support)
The support body 1 and the support body 2 were produced by the process shown below using a JIS A 1050 aluminum plate having a thickness of 0.3 mm.

(A) Mechanical surface roughening treatment While supplying a suspension of abrasive (silica sand) having a specific gravity of 1.12 and water as a polishing slurry liquid to a surface of an aluminum plate, it is mechanically rotated by a roller-like nylon brush. Roughening was performed. The average particle size of the abrasive was 8 μm, and the maximum particle size was 50 μm. The material of the nylon brush was 6 · 10 nylon, the hair length was 50 mm, and the hair diameter was 0.3 mm. The nylon brush was planted so as to be dense by making a hole in a stainless steel tube having a diameter of 300 mm. Three rotating brushes were used. The distance between the two support rollers (φ200 mm) at the bottom of the brush was 300 mm. The brush roller was pressed until the load of the drive motor for rotating the brush became 7 kW plus with respect to the load before the brush roller was pressed against the aluminum plate. The rotating direction of the brush was the same as the moving direction of the aluminum plate. The rotation speed of the brush was 200 rpm.

(B) Alkali etching treatment The aluminum plate obtained above was sprayed with an aqueous NaOH solution at a temperature of 70 ° C. (concentration 26 mass%, aluminum ion concentration 6.5 mass%) to perform an etching treatment, and the aluminum plate was 6 g / m. ² dissolved. Thereafter, washing with water was performed using well water.

(C) Desmutting treatment Desmutting treatment was performed by spraying with a 1% by weight aqueous solution of nitric acid at a temperature of 30 ° C. (containing 0.5% by weight of aluminum ions), and then washed with water by spraying. The nitric acid aqueous solution used for the desmut was the waste liquid from the step of electrochemical surface roughening using alternating current in nitric acid aqueous solution.

(D) Electrochemical roughening treatment An electrochemical roughening treatment was carried out continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a nitric acid 10.5 g / liter aqueous solution (aluminum ion 5 g / liter) at a temperature of 50 ° C. The AC power supply waveform has an electrochemical surface roughening treatment using a carbon electrode as a counter electrode using a trapezoidal rectangular wave alternating current with a time TP of 0.8 msec until the current value reaches a peak from zero, a DUTY ratio of 1: 1. went. Ferrite was used for the auxiliary anode. The electrolytic cell used was a radial cell type.
The current density was 30 A / dm ² at the peak current value, and the amount of electricity was 220 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode. 5% of the current flowing from the power source was shunted to the auxiliary anode.
Thereafter, washing with water was performed using well water.

(E) Alkali etching treatment The aluminum plate was sprayed at a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass at 32 ° C. to dissolve the aluminum plate by 0.20 g / m ² , The smut component mainly composed of aluminum hydroxide generated when electrochemical surface roughening was used was removed, and the edge portion of the generated pit was melted to smooth the edge portion. Thereafter, washing with water was performed using well water.

(F) Desmut treatment Desmut treatment was performed by spraying with a 15% by weight aqueous solution of nitric acid at a temperature of 30 ° C. (containing 4.5% by weight of aluminum ions), and then washed with water using well water. The nitric acid aqueous solution used for the desmut was the waste liquid from the step of electrochemical surface roughening using alternating current in nitric acid aqueous solution.

(G) Electrochemical surface roughening treatment An electrochemical surface roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a hydrochloric acid 7.5 g / liter aqueous solution (containing 5 g / liter of aluminum ions) at a temperature of 35 ° C. The AC power supply waveform was a rectangular wave, and an electrochemical surface roughening treatment was performed using a carbon electrode as a counter electrode. Ferrite was used for the auxiliary anode. The electrolytic cell used was a radial cell type.
The current density was 25 A / dm ² at the peak current value, and the amount of electricity was 50 C / dm ² in terms of the total amount of electricity when the aluminum plate was the anode.
Thereafter, washing with water was performed using well water.

(H) Alkali etching treatment The aluminum plate was sprayed at a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass at 32 ° C. to dissolve the aluminum plate at 0.10 g / m ² , The smut component mainly composed of aluminum hydroxide generated during the electrochemical surface roughening treatment was removed, and the edge portion of the generated pit was dissolved to smooth the edge portion. Thereafter, washing with water was performed using well water.

(I) Desmut treatment A desmut treatment by spraying was performed with a 25% by mass aqueous solution of sulfuric acid having a temperature of 60 ° C. (containing 0.5% by mass of aluminum ions), and then water washing by spraying was performed using well water.

(J) Anodizing treatment As the electrolytic solution, sulfuric acid was used. The electrolyte solutions all had a sulfuric acid concentration of 170 g / liter (containing 0.5 mass% of aluminum ions), and the temperature was 43 ° C. Thereafter, washing with water was performed using well water.
Both current densities were about 30 A / dm ² . The final oxide film amount was 2.7 g / m ² .

(K) Alkali metal silicate treatment An aluminum support obtained by anodizing treatment was immersed in a treatment layer of a 1 mass% aqueous solution of sodium silicate No. 3 at a temperature of 30 ° C. for 10 seconds to immerse the alkali metal silica. Acid salt treatment (silicate treatment) was performed. Then, the water washing by the spray using well water was performed. The amount of silicate adhering at that time was 3.5 mg / dm ² .

<Support 1>
The above steps (a) to (k) were sequentially performed, and the support 1 was produced such that the etching amount in the step (e) was 3.5 g / m ² .

<Support 2>
Except for omitting the steps (g), (h), and (i) among the above steps, each step was performed in order to prepare the support 2.

<Support 3>
Except for omitting the steps (a), (g), (h) and (i) among the above steps, the respective steps were performed in order to prepare the support 3.

(Formation of intermediate layer)
The following coating solution for forming an intermediate layer was applied onto the support 1 produced as described above, and then dried at 80 ° C. for 15 seconds to provide an intermediate layer. The coating amount after drying was 15 mg / m ² .

<Intermediate layer forming coating solution>
・ The specific polymers listed in Table 1 0.3 g
・ Methanol 100g
・ Water 1g

[Formation of recording layer]
-Synthesis of Copolymer 1-
A 500 ml three-necked flask equipped with a stirrer, a condenser tube and a dropping funnel is charged with 31.0 g (0.36 mol) of methacrylic acid, 39.1 g (0.36 mol) of ethyl chloroformate and 200 ml of acetonitrile and cooled in an ice water bath. The mixture was stirred while. To this mixture, 36.4 g (0.36 mol) of triethylamine was dropped with a dropping funnel over about 1 hour. After completion of the dropwise addition, the ice-water bath was removed, and the mixture was stirred at room temperature for 30 minutes.

  To this reaction mixture, 51.7 g (0.30 mol) of p-aminobenzenesulfonamide was added, and the mixture was stirred for 1 hour while warming to 70 ° C. in an oil bath. After completion of the reaction, the mixture was added to 1 liter of water with stirring, and the resulting mixture was stirred for 30 minutes. The mixture was filtered to take out a precipitate, which was slurried with 500 ml of water, then the slurry was filtered, and the obtained solid was dried to dry a white solid of N- (p-aminosulfonylphenyl) methacrylamide. Was obtained (yield 46.9 g).

  Next, 4.61 g (0.0192 mol) of N- (p-aminosulfonylphenyl) methacrylamide and 2.58 g of ethyl methacrylate (0.0258 mol) were added to a 200 ml three-necked flask equipped with a stirrer, a condenser and a dropping funnel. ), 0.80 g (0.015 mol) of acrylonitrile and 20 g of N, N-dimethylacetamide were added, and the mixture was stirred while heating to 65 ° C. with a hot water bath. To this mixture, 0.15 g of 2,2′-azobis (2,4-dimethylvaleronitrile) (trade name: “V-65”, manufactured by Wako Pure Chemical Industries, Ltd.) was added as a polymerization initiator and maintained at 65 ° C. The mixture was stirred for 2 hours under a nitrogen stream. To this reaction mixture, 4.61 g of N- (p-aminosulfonylphenyl) methacrylamide, 2.58 g of methyl methacrylate, 0.80 g of acrylonitrile, 20 g of N, N-dimethylacetamide and 0.15 g of the above “V-65” were added. The mixture was added dropwise via a dropping funnel over 2 hours. After completion of the dropwise addition, the resulting mixture was further stirred at 65 ° C. for 2 hours. After completion of the reaction, 40 g of methanol was added to the mixture, cooled, and the resulting mixture was added to 2 liters of water while stirring the water. After stirring the mixture for 30 minutes, the precipitate was removed by filtration and dried. 15 g of a white solid was obtained. It was 54,000 when the weight average molecular weight (polystyrene standard) of this specific copolymer 1 was measured by the gel permeation chromatography.

(Formation of recording layers of Examples 1, 3, 5, 6, and 8)
The following recording layer forming coating solution 1 was coated on the support obtained as described above (described in Table 1) so that the coating amount was 0.85 g / m ² , and then manufactured by TABI Corporation, PERFECT The wind control was set to 7 in OVENPH200 and dried at 110 ° C. for 50 seconds. Thereafter, the recording layer forming coating solution 2 was applied so that the coating amount was 0.30 g / m ^2, and then dried at 120 ° C. for 1 minute, and the planographic printing plates of Examples 1, 3, 5, 6, and 8 were used. I got the original version.

<Recording layer forming coating solution 1>
-Copolymer 1 2.133 g
・ Cyanine dye A (the following structure) 0.109 g
・ 4,4'-bishydroxyphenylsulfone 0.126g
・ Tetrahydrophthalic anhydride 0.190g
・ 0.008 g of p-toluenesulfonic acid
・ 3-methoxy-4-diazodiphenylamine hexafluorophosphate 0.030 g
・ The ethyl violet counter ion was changed to 6-hydroxy-2-naphthalenesulfonic acid anion 0.100 g
・ Megafac F780, manufactured by Dainippon Ink & Chemicals, Inc. (Coated surface-modified fluorine-based surfactant) 0.035 g
・ Methyl ethyl ketone 25.38g
・ 13.0 g of 1-methoxy-2-propanol
・ Γ-butyrolactone 13.2 g

<Recording layer forming coating solution 2>
・ M, p-cresol novolak (m / p ratio = 6/4, weight average molecular weight 4500, containing 0.8% by mass of unreacted cresol) 0.3478 g
・ The cyanine dye A 0.0192g
・ The following onium salt B 0.0115g
・ Megafac F780 (20%), manufactured by Dainippon Ink & Chemicals, Inc. (Surface improving surfactant) 0.022 g
・ Methyl ethyl ketone 13.07g
1-methoxy-2-propanol 6.79g

(Formation of recording layers of Examples 2, 4, and 7)
The following image forming layer coating solution 3 was applied on the support 1 obtained as described above so that the coating amount after drying was 1.2 g / m ² , and the planographic printing of Examples 2, 4, and 10 I got the original version.

<Recording layer forming coating solution 3>
・ M, p-cresol novolak 0.93g
(M / p ratio = 6/4, weight average molecular weight 7,300,
Unreacted cresol 0.4% by mass
・ The following vinyl polymer (1) 0.07g
・ Infrared absorber (the cyanine dye A) 0.017 g
・ Infrared absorber (cyanine dye B below) 0.023g
・ 2,4,6-Tris (hexyloxy)
Benzenediazonium-2-hydroxy-4-methoxybenzophenone-5-sulfonate 0.01 g
・ 0.003 g of p-toluenesulfonic acid
・ Cyclohexane-1,2-dicarboxylic anhydride 0.06g
・ Counter anion of Victoria Pure Blue BOH
1-naphthalenesulfonic acid anion dye 0.015g
・ Fluorine-based surfactant 0.02g
(Megafuck F-176, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 15g
・ 7g of 1-methoxy-2-propanol

[Comparative Example 1]
The lithographic plate of Comparative Example 1 was prepared in the same manner as in Example 1, except that the following comparative polymer (PA-0) was used instead of the specific polymer (P-1) in the intermediate layer forming coating solution of Example 1. A printing plate master was obtained.

[Comparative Example 2]
In Example 1, a lithographic printing plate precursor of Comparative Example 2 was obtained in the same manner as in Example 1 except that no intermediate layer was provided.

<Evaluation>
The resulting lithographic printing plate precursors of Examples 1 to 8 and Comparative Examples 1 and 2 were exposed and developed as described below to obtain lithographic printing plates. Each lithographic printing plate obtained was evaluated as follows for stain resistance and printing durability of non-image areas.
[Exposure / Development]
The obtained planographic printing plate precursors of Examples 1 to 8 and Comparative Examples 1 and 2 were imagewise exposed at a setter exposure of 8.0 W and 150 rpm using a TrendSetter 3244F manufactured by CREO.
Next, each of the lithographic printing plate precursors of Examples 1 to 5 and Example 8 and Comparative Examples 1 and 2, manufactured by Fuji Photo Film Co., Ltd., which is a developer containing substantially no alkali metal silicate. The developer for a lithographic printing plate DT-2 was used under the standard use conditions, and each lithographic printing plate precursor of Examples 6 and 7 was a developer containing an alkali metal silicate (development for a PS plate made by Fuji Photo Film). Using the liquid DP-4) under standard use conditions, each was developed with an automatic processor 900NP. Thereby, each lithographic printing plate of Examples 1-5, Example 8, and Comparative Examples 1 and 2 was obtained.

1. Evaluation of stain resistance in non-image area Using each of the obtained lithographic printing plates, a Mitsubishi diamond F2 printing machine (manufactured by Mitsubishi Heavy Industries, Ltd.) was used to print using DIC-GEOS (s) red ink, and 10,000 The stain on the blanket after printing the sheets was visually evaluated.
The evaluation criteria were ◎ for those that were not soiled at all, ◯ for those that were hardly soiled, and × for those that were significantly soiled. The results are shown in Table 1.

2. Evaluation of printing durability Each lithographic printing plate obtained was printed using a DIC-GEOS (N) black ink manufactured by Dainippon Ink & Chemicals, Inc. on a Lislon printing machine manufactured by Komori Corporation. Printing durability was evaluated based on the number of printed sheets when it was visually recognized that the density began to decrease. The results are shown in Table 1.

As shown in Table 1, the lithographic printing plate precursors of Examples containing the specific polymer in the intermediate layer, stain resistance in the non-image portion, and it is understood that those were excellent in printing durability. The polymer (PA-0) used in Comparative Example 1 is a polymer that is widely used in the intermediate layer of a conventional lithographic printing plate precursor. From the comparison between Examples 1 and 5 and Comparative Example 1 prepared under the same conditions except for the intermediate layer polymer, by adding the specific polymer to the intermediate layer, the stain resistance in the non-image area is kept good. It can also be seen that the printing durability was further improved. In Comparative Example 2 where no intermediate layer is provided, it can be seen that the printing durability and the stain resistance in the non-image area are inferior to those of the Examples.
Further, the lithographic printing plate precursor of the example containing the specific polymer in the intermediate layer may be obtained by using an alkali metal silicate even when a developer (non-silicate developer) containing substantially no alkali metal silicate is used. It has been found that even when a developer containing a salt (silicate developer) is used, a lithographic printing plate that can be developed satisfactorily and has no practical problems can be obtained.

Claims (1)

The support contains a polymer having a repeating unit having a cation structure, a group having an alkali-dissociative proton and a counter anion containing a sulfonate ion (—SO ₃ ⁻ ) in the side chain as a constituent component. A lithographic printing plate precursor comprising an intermediate layer and a photosensitive positive recording layer whose solubility in an aqueous alkali solution is improved by exposure in this order.